After oxygen theoretically ran out on the missing OceanGate submersible on Thursday, drastically cutting down on the chances that the five onboard the vessel will be found alive, an unconfirmed audio clip of the “banging” sounds reportedly picked up by the marine officials engaged in a desperate search and rescue mission on the Atlantic Ocean, has gone viral.

The clip first began circling on TikTok before finding its way into Twitter. Here is the clip:

The authenticity of the audio snippet that first surfaced online on Wednesday, June 21, has been brought into question. In the audio, after a brief sonar ping, very faint knocking sounds can be heard amid a lot of background noises. “Actual audio was never released,” one user wrote on Twitter while another commented, “From where did you get this recording? What proof is there that this is related to the Titan rescue search and not a sound clip someone put together? The *experts* in underwater sound said that the sounds they heard were *inconclusive*.”

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The original noises were first reported to be picked up by a Canadian aircraft searching for the missing vessel detected noises with its sonar technology. The banging sounds were heard by a P-3 surveillance plane, which seemed to happen every 30 minutes. It stopped for a bit before again being detected four hours later when additional sonar devices were deployed.

However, the US Coast Guard has said that they “don’t know the source of the noise.” CNN obtained a memo that said the banging indicates “continued hope of survivors” and will “assist in vectoring surface assets”. However, Coast Guard Jamie Frederick said analysis of the sounds has been “inconclusive” as the search and rescue mission has not yielded any positive results yet.

Also Read | Did Titan Five run out of oxygen at 7:08 am EST? Experts say air time on OceanGate submersible is not fixed

Five people who are onboard the submersible are British billionaire Hamish Harding, businessman Shanzada Dawood and his son Suleman, pilot Paul-Henri Nargeolet, and OceanGate CEO Stockton Rush.